Yellowstone National Park: Petrified Trees

We tried to go up to see the Petrified Trees; however, a herd of bison decided to march by us.
An hour or so later, we made it up. Petrified trees are form when plants are trapped beneath other materials. Later, the plants decay and materials get into the cast left, and these create stone trees that look just like real plants. The more popular site near Roosevelt is now behind glass as tourists continually took pieces with them; however, this lesser known spot was an incredible look at geology in action.